Here you can add documentation and descriptions to help users properly understand the functionality of your custom web parts. This documentation will be displayed when clicking the information icon in the top right corner of the configuration dialog of the given web part.
If you wish to document particular properties, you need to fill in the Field description on the Properties tab.
You can generate complete web part documentation and print it by going to <website URL>/CMSPages/Dialogs/documentation.aspx?generate=full in your browser. If you want to print it, it's recommended that you use FireFox for correct formatting and page breaking.
More resources can be found at: